Radiolytic destruction of nonbiodegradable organic pesticides

ABSTRACT

This invention relates to a method for treating industrial waste solutions containing nonbiodegradable organic pesticides which comprises saturating the solution with oxygen and then irradiating the pressurized solution until the pesticide has been decomposed into nontoxic constituents to that degree required for safe disposal.

0 United States Patent 1151 3,640,808

Case et al. 1 Feb. 8, 1972 [54] RADIOLYTIC DESTRUCTION OF NONBIODEGRADABLE ORGANIC (defence-8 Cmd PESTICIDES UNITED STATES PATENTS [721 lflvemors= f-C Ridge, Tenth; Arthur 3,537,966 11/1970 Steinberg ..204/157.1 H Garmon, watkmsvlllei d Donald 3,553,089 1/1971 Mytelka et a1 ..204/158 HE Kau, Rockwood; David E. Smiley, Knox- Ville, both of Primary Examiner-Howard S. Williams [73] Assignee: The United States of America as Attorney-Roland Anderson represented by the United States Atomic Energy Commission [57] ABSTRACT [22] Filed Oct 7 1969 This invention relates to a method for treating industrial waste solutions containing nonbiodegradable organic pesticides [21] Appl. No.: 864,521 which comprises saturating the solution with oxygen and then irradiating the pressurized solution until the pesticide has been decomposed into nontoxic constituents to that degree 52 us. (:1 ..204/1ss HE required for Safe disposaL [51] Int. Cl. ..B0lj 1/10 [58] Field 0! Search ..204/157.l H, 158 HE 1 Claims, No Drawings RADIOLYTIC DESTRUCTION OF NONBIODEGRADABLE ORGANIC PESTICIDES BACKGROUND OF THE INVENTION The invention described herein was made in the course of, or under, a contract with the U.S.A.E.C. It relates generally to the area of pesticide pollution, and more particularly to a method for treating liquid industrial waste streams containing halogenated hydrocarbons having pesticidal activity.

It has become standard practice in many textile and carpet manufacturing facilities to treat textile fibers and cloth with organic pesticides dissolved in organic solvents or dispersed in aqueous media. A principal class of pesticide used for this purpose is selected from the group consisting of halogenated, particularly chlorinated, hydrocarbons which are highly nonbiodegradable, i.e., in the sense that they are highly resistant to being broken down by nature into harmless components. It has by now been fairly well established that, when released to natural environments, they persist for many years, causing harmful effects on the normal ecological balance. Typical halogenated hydrocarbons having pesticidal action which are found and used in liquid effluent streams are, but are not limited to, such pesticides as endrin, dieldrin, aldrin, chlordan, toxaphene, lindane, methoxychlor, heptachlor, 2,4-D, 2,4,5-T, and DDT, as these terms are defined in the 1956 and subsequent editions of the Condensed Chemical Dictionary, published by Reinhold Publishing Company.

Recognizing that the toxicity of these pesticide-containing liquid effiuents must be reduced as a matter of public health and safety, methods have been devised for treating such wastes based on anaerobic lagooning or fermentation techniques. While studies show that nonbiodegradable hydrocarbons can be reduced by about 90 percent over a period of a month or more, liquid wastes treated by these methods still contain harmful levels of pesticide. Nevertheless, such effluents are released into surrounding natural streams and dilution effects are relied upon to reduce the potential harmful effects. It is therefore clear that industrial waste treatments are only partially effective to reduce pesticide concentration. Such treatments require an inordinate amount of time to produce, at best, a partially effective result.

SUMMARY OF THE INVENTION It is the principal object of this invention to provide a method for treating pesticide-containing liquid waste streams in an efficient, effective manner to reduce their concentration or to convert them to harmless components in a relatively short time.

This and other objects of the invention are met by saturating liquid wastes of the character defined with oxygen by pressurizing such liquids to a partial pressure of oxygen or air of at least 300 p.s.i. and then subjecting the pressurized liquid to a gamma dosage sufficient to reduce the concentration of pesticide to an acceptable, safe level for disposal to the natural environment. Under these general conditions, the amount of pesticide can be reduced by at least an order of magnitude in some cases within a period of minutes at total gamma dosages ranging from i to 2 megaroentgen. The dramatically beneficial effects of this invention are most apparent when the pesticide is in solution or in an extremely finely dispersed phase. It is not effective where the pesticide is not dispersed or where high-pressure radiolysis will result in precipitation. It is most effective where the pesticide concentration is in the parts-permillion range and thus at a concentration where prior art methods are least effective.

The following representative examples will illustrate the effectiveness of the invention in reducing the pesticide known as dieldrin, a nonbiodegradable aqueous-insoluble pesticide.

Example I A feed solution containing 20 parts per million (p.p.m.) dieldrin emulsified in H O was charged into a glass-lined stainless steel pressure vessel pressurized with an oxygen-containmg atmosphere using either pure oxygen or air and the TABLE I Irradiation Dieldrin, Percent Experiment time, p.p.m. pesticide No. hrs. Conditions (by weight) removed 1 Atm.press 7. 1 64. 5

1 1,800 D.S.i.Oz 0. 2 99. 0

1 1.880p.s.i.air... 0.3 98. 5

0 1,800p.s.i. 02.... 13. 5 32. 5

0 1.800p.s.i.air 14. 0 30. 0

It can be seen that the analyses for dieldrin before and after irradiation to a total dosage of 8X10 r. with and without pressurized oxygen or air showed dramatically how the pesticide could be rapidly and substantially eliminated from the test solutions. The use of pressure alone or radiation alone is only partially effective and highlights the extreme advantage of combining a pressurized oxygen-containing atmosphere with radiation to achieve a rapid radiolytic destruction of the pesticide. Destruction of the pesticide is monitored by chromatographic techniques and can also be followed by measuring the pH of the pressurized solution. As the chlorinated hydrocarbon is destroyed, it apparently releases chloride ion, which combines with any water present to acidify the irradiated liquid.

Example II An aqueous feed solution containing 5 p.p.m. dieldrin was irradiated under an oxygen pressure of L800 p.s.i. with a cobalt-60 source at a dose rate of 8X10 r./hr. for periods of from l5 to 30 minutes. The results are summarized in Table II What is claimed is:

1. A method for treating industrial waste solutions containing nonbiodegradable organic pesticides which comprises pressurizing said solution with an oxygen pressure of from 300 to l,800 p.s.i. and then irradiating the pressurized solution to a point where the solution has been acidified and at least percent of the pesticide has been destroyed. 

